An international team of researchers, including from Princeton University, has apparently debunked Stephen Hawking’s theory that mysterious dark matter might be made up of tiny black holes created at the beginning of the universe.
The elusive dark matter — which is supposed to be responsible for 85 percent of the universe’s mass — remains hypothetical because all attempts to detect its particles through experiments have failed so far.
Scientists are familiar with regular black holes, which are created when a giant star explodes and the remaining core is so huge that it collapses under its own gravity.
Hawking proposed a different, much smaller kind of black hole.
According to his hypothesis, black holes could have formed in the primordial stages of the universe long before the first stars formed.
At that time, all matter was clouds of gas, some of which could have clumped together and collapsed into very small black holes, according to Popular Mechanics.
Because they didn’t form from stars, these tiny black holes might weigh less than a milligram. If enough of them formed in the early years of the universe, they may account for most — or all — of the undetected dark matter.
A team led by Kavli Institute for the Physics and Mathematics of the Universe in Japan and including researchers from Princeton, the Inter-University Centre for Astronomy and Astrophysics in India, the University of Tokyo and Osaka University used a telescope in Hawaii to observe the Andromeda Galaxy, the Milky Way’s closest neighbor.
They searched for the telltale signs of minuscule black holes, some of which would theoretically pass in front of some of the stars in Andromeda, distorting it slightly.
If Hawking’s hypothesis was right, you’d expect to see about 1,000 such flickers.
But they saw one, which means that primordial black holes can be responsible for no more than 0.1 percent of dark matter.
Their finding doesn’t unequivocally prove that Hawking, the theoretical physicist who died a year ago at age 76, was wrong.
But it means we have to continue searching for the source of dark matter — and perhaps this mystery will never be solved.
“Our research demonstrated that primordial black holes can’t be dark matter candidates. The theorists have to find out an alternate theory,” Indian astrophysicist Surhud More told the Deccan Herald.
“The results have now confirmed that primordial black holes with masses similar or less massive than the moon can’t contribute more than a percent of all dark matter,” Surhud said.